The invention relates to a display device having a viewable side and pixel elements which are reversibly switchable between at least a first state of reflecting light and a second state of absorbing light, said pixel elements comprising a stack of layers including a switchable layer of an optically switchable material which brings about a switch from the first state to the second state of the pixel element, said layer being switched by electric switching means.
U.S. Pat. No. 5,905,590 describes a switching device comprising a switching film including hydrides of gadolinium or other trivalent metal. By exchange of hydrogen, the switching film can be reversibly switched from a transparent state to a mirror-like state with zero transmission via an intermediate black absorbing state. The switching film is comprised in a stack of layers, which is deposited on a transparent substrate. By making a pattern in the switching film and providing the patterned switching film with transparent electrodes, a thin display can be manufactured. The display is viewed from a side of the substrate on which the stack is deposited.
The display is driven by switching means. The switching means are comprised in the pixel elements and determine the aperture ratio of the display, i.e. the ratio of the display area of the display, which is effective in the switching with respect to the total surface area of the display.
It is an object of the invention to provide a switching mirror device, which has an increased aperture ratio. To this end, the invention is characterized in that the electric switching means are positioned behind the layer of optically switchable material with respect to the viewable side of the display device. Thus, the electric switching means no longer determine the aperture ratio of the display, and therefore the aperture ratio is increased considerably.
Advantageous embodiments of the invention are described in the dependent claims.
These and other aspects of the invention will be elucidated with reference to the embodiments described hereinafter.